Chapter 9: Unix and Other Operating System Philosophies

Overview

At this juncture, it is appropriate to engage in a short discussion of the philosophies of a few other operating systems besides Unix. We're not going to delve deeply into this area, as we do not intend to embark upon a treatise on comparative operating system philosophies. But a brief foray into several other "religions" of the software world should prove enlightening, if only to illuminate why the Unix approach is such a radical departure from other software design methodologies.

We will look at the design philosophies of three historical operating systems in this chapter. Each had achieved success in its respective niche. Each had developed a following of loyal devotees. Each shares some commonality with Unix and Linux, and each bears some characteristics that set it apart, sometimes in striking ways.

For a variety of reasons, not the least of which was limited hardware capacity, these operating systems were written for specific hardware platforms. Users needed strong justification to shell out several thousand to several million dollars for systems that were relatively inflexible. You did not have thousands of applications available at discount retailers and flea markets. Personal computers were not cheap and plentiful. Few people had old computers collecting dust on the tops of piles of unused household goods in their basements.

Newer, faster hardware eventually came along, causing these OSs to fall into disuse. Without the portability of Unix, they could not keep up as hardware designers produced machines with increasing amounts of storage, specialized peripherals, and advanced graphics capabilities. The one exception here is Microsoft's Disk Operating System (MS-DOS). MS-DOS is not a portable operating system, however. It was ported to progressively more powerful machines, but they were all of essentially the same architecture. In more recent versions of Windows, Microsoft has all but eliminated MS-DOS altogether in favor of the Windows API and GUI.

Although the operating systems discussed here have themselves largely faded into obscurity, their design philosophies still exist today in one form or another. For example, while production of the Atari Home Computer ceased long ago, the human engineering concepts found in its operating system continue to be implemented and refined in today's hottest game machines.

If I manage to misinterpret the original intent of the operating system designers, I offer my apologies. As you might suspect, documented operating system philosophies are hard to come by. I can only hope that I have caught the essence of the designers' goals in some fashion. For our purposes, though, absolute accuracy is less important than the general thread of the design methodology in a holistic sense. In that respect, the following discussions should serve us well.